The present invention relates to an electronic digital scale, wherein a length is measured through the movement of an extensible member and is indicated in a digital display unit after being processed by computation circuits.
In the past it has been proposed that an electronic digital scale system employ a tape means including a plurality of marks or sprocket holes at predetermined intervals for measuring the length of the tape pulled out of the housing of the electronic digital scale. The length of the tape is determined through the measurement of the number of transited marks or sprocket holes detected at an optical sensing means. However the marks and sprocket holes may be damaged or obstructed by an operator while he handles the tape means including the marks and the sprocket holes, and this prevents the measurement through the use of an optical sensing means.